On Oct 31, 8:59 pm, smcjensen wrote:
On Oct 31, 1:09 pm, Drew Cutter wrote:

I have to replace a smash vent on the roof. I thought this would be a
good time to put in a power air vents. Any down side ? solar ?

I installed a fan in one of the gable end vents a few summers ago. I
also built a baffle so it wouldn't suck air into the same vent then
just blow it right back out. I have other gable vents in the attic
and soffit vents as well. Fan was placed in one of the uppermost
gables. I did some before and after testing and the power vent
brought the attic temp down about 15 degrees which is pretty
significant. I'm in NC and have a 2 AC house. It makes sense that an
AC unit in a 115 degree attic would have less work to do than one in a
130 degree attic. Upstairs is appreciably more comfortable and on the
really hot days, the upstairs AC used to run seemingly all day long.

If upstairs AC is also a gas furnace, you need to wire the fan so that
it won't go on if the furnace is on as it can disrupt the flow of
gases up the flue.

If the fan has a thermostat set at any reasonable temp, why would the
attic fan ever go on when the furnace is running? My attic doesn't
get to 100 deg+ when I need the furnace on.